Diamonds have historically been the most popular of all gemstones, and are frequently used in wedding bands, engagement rings, pendants, earrings, and other types of jewelry. Because of their popularity and additional market forces, diamonds are generally more expensive than other gemstones. As a result, diamond simulants that simulate the optical properties of diamonds but at a fraction of the cost are becoming increasingly popular. Additionally, with the growing awareness of conflict diamonds, there is increased consumer apprehension regarding the origin of diamonds and thus increased consumer reluctance to purchase authentic diamonds. As such, there has been a growing demand for synthetic diamonds and diamond simulants, such as cubic zirconia and moissanite.
Cubic zirconia is a cubic crystalline form of zirconium dioxide that is hard, can be optically flawless, and is often colorless. Because of its durability, generally low cost to produce, and visual likeness to diamond, cubic zirconia is commonly used as a diamond simulant. Despite having a visual appearance close to that of diamond, there are notable characteristics distinguishing cubic zirconia from diamond.
For example, diamond has a hardness of 10.0 on the Mohs hardness scale whereas cubic zirconia has a hardness of 8.0. A diamond has a light refractive index 2.417 whereas cubic zirconia has a light refractive index of approximately 2.2. A diamond has a dispersion value of 0.044 nm whereas cubic zirconia has a dispersion value of approximately 0.06 nm. Cubic zirconia weighs approximately 1.7 times more than diamond of an equivalent size. A diamond may also have a yellow tint. Any color present in a cubic zirconia gemstone is typically the result of an additive.
Thus, while there are significant similarities between cubic zirconia and diamond that make cubic zirconia a popular diamond simulant, there are significant differences between cubic zirconia and diamond that make consumers reluctant to purchase a cubic zirconia instead of a diamond. For example, cubic zirconia is brittle compared to a diamond, and thus is less durable and prone to scratching. Also, colorless cubic zirconia will give off a rainbow-like reflection that is not found in genuine diamonds.